DKW 173 – year 1924
Manufacturer: Zschopauer Motorenwerke, J. S. Rasmussen AG, Zschopau, Saxony, Germany
Demand for motorcycles with better and better parameters, which were decisive for success in racing, forced designers to build stronger and more efficient drive units. Successful idea with engine supercharging, already used in Bekamo motorcycles by Berliner Kleinmotoren, he became a role model also for J.. S. Rasmussen, owner of the DKW company.
The first DKW power unit supercharged with a reciprocating compressor was built in 1924 year. It was a two-stroke engine with a displacement 173 cm3 and fairly simple design. Piston with deflector, directing the flow of the mixture, ensure good flushing of the combustion chamber. There was a second cylinder at the bottom of the crankcase, in which the compressor piston was moving. This piston "helped to enlarge” capacity when sucking fuel with air into the crankcase, and on the compression stroke, it pushed the mixture into the combustion chamber.
On DKW motorcycles equipped with the described engine 173 cm3, two types of frame were used. The abbreviation ZM stood for a model with a classic tubular frame, and the abbreviation SM meant DKW with a frame welded from stamped sheet metal elements. The front suspension with a swinging fork was sprung by two springs (one working in compression, second – on stretching). The engine drove a leather V-belt pulley attached to the spokes of the rear wheel. The brakes only acted on the rear wheel. Exhaust pipe (with a special shape) it had a good damping effect and prevented disturbances in the exhaust gas flow.
Already two years after the publication of "Pile of seventy” on the market, DKW launched this model also in motorcycle sport. In the years 1926-1930 there were probably no major races, in which DKW motorcycles would not score points for victories.